Query : 1997A&A...318L..35C

1997A&A...318L..35C - Astronomy and Astrophysics, volume 318, L35-38 (1997/2-2)

DI in the outer Galaxy.


Abstract (from CDS):

We report on a deep search with the Westerbork Synthesis Radio Telescope towards the galactic anticenter for the 327MHz hyperfille transition of DI. This is a favorable direction for a search because: (i) the HI optical depth is high due to velocity crowding; (ii) the observed molacular column density is low (implying that most of the deuterium would probably be in atomic form, rather thall in HD); and (iii) the stellar reprocessing should be minimal. Our observations are about a factor of two more sensitive than previous searches for DI in this direction. We detect a low significance (∼4σ) feature, consistent in both amplitude and center frequency with an emission feature reported previously (Blitz & Heiles 1987ApJ...313L..95B). If this is the DI line, then the implied ND/NH of 3.9±1.0x10–5 is comparable to the inferred pre-solar deuterium abundance. Our observation is consistent with the recent low measurements of D/H towards high-redshift Lyman-limit systems. On the other hand, if the reports of high DI abundance (∼24x10–5) in such systems are confirmed, then our observations imply that even in regions of reduced star formation within the outer Galaxy, the DI abundance has been reduced by a factor of ∼6 from the primordial abundance.

Abstract Copyright:

Journal keyword(s): Cosmology: observations - ISM: abundances - Galaxy: abundances - Radio lines: ISM

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 NAME Sgr A Region reg 17 45 12 -28 48.3           ~ 931 0
2 NAME Cas A SNR 23 23 24.000 +58 48 54.00     14.30     ~ 2591 1

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